Drivers of early model vehicles that have their original steering configuration, often experience vagueness in steering while driving. This is a result of worn component such as the original steering box and steering linkages.
Vehicles from the 1960's and 70's, often referred to as muscle cars, typically have recirculating ball steering arrangements which are known to have a “dead spot” on centre. This dead spot means that a small turn of the steering wheel does not influence the vehicle's direction of travel.
Furthermore the steering of older vehicles often display mechanical play, slow response and poor centring capabilities.
These vehicles typically did not include power assisted steering systems. This, combined with their weight results in a significant amount of effort being required to turn the steering wheel, especially at low speed.
Simply rebuilding the existing steering systems of these vehicles using new gears, bearings and linkages may reduce the mechanical play. The feel of the steering does not however compare to the performance of modern power assisted rack and pinion steering systems. As a result many owners opt to replace the original mechanical steering systems with rack and pinion powered assisted steering, which utilize a hydraulic pump to increase the ease of steering at low speed.
Conventional rack and pinion steering systems include a rack, having teeth along one side, adapted to engage a toothed end of a pinion shaft. The opposite end of the pinion shaft is connected to the steering wheel shaft by way of a universal joint.
The rack is connected to opposing front wheels by way of corresponding tie rods. This means that the circular motion of the steering wheel and pinion shafts is converted into rectilinear movement of the rack and tie rod ends. There are many advantages with modern rack and pinion steering systems, including that they eliminate the on-centre spot and offer improved steering accuracy, reduced effort, and considerably improved tracking ability.
A popular type of rack and pinion steering system is the centre takeoff systems, which enable correct geometry and an optimum level of positive and direct steering. Centre takeoff systems include a pinion and a rack having a toothed portion and a shaft portion, wherein the rack is connected to a drag link that in turn is connected to the tie rod ends. This construction is more compact than the “enddriven” design rack and pinion systems, where the tie rods connect directly to opposing ends of the rack.
Due to their many advantages, power assisted rack and pinion conversions have become a popular option for owners of cars such as the Pontiac GTO, Ford Mustang and Chevrolet Corvette. This is especially the case when cars are being converted between left and right hand drive because the owner is already required to replace or modify the steering system.
One of the problems with existing centre takeoff rack and pinion assemblies, is they typically need to be custom made for each make and model of vehicle. This is because the pinion needs to be at a different angle for different types of vehicle to take into account the particular constraints of the Y-frame, the configuration of the engine bay and placement of components therein.
Furthermore the centre takeoff rack and pinion system has to allow placement of the steering rack to provide adequate clearance for both long and short tube exhaust manifolds, or aftermarket components within the engine bay. There may also be physical constraints arising from converting a vehicle between left and right hand drive.
An object of the present invention is to ameliorate one or more of the above described difficulties, or at least provide a useful alternative to steering arrangements of the type discussed above.
Other advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, several embodiments of the present invention are disclosed.